The Interstate 5 bridge over the Skagit River in northern Washington state collapsed Thursday evening. / Anonymous

by William M. Welch, USA TODAY

by William M. Welch, USA TODAY

The Interstate 5 bridge over the Skagit River in northern Washington state collapsed Thursday evening, sending vehicles and people into the water, the state patrol said. Authorities said there were no deaths, and three people were taken to hospitals.

Trooper Mark Francis told USA Today that no cause for the collapse was known at this time, and it was unknown how many vehicles were in the water.

Kari Ranten, a spokeswoman for Skagit Valley Hospital, said two people who were injured were en route to the facility. She said another person was being transported to a different area hospital.

Washington state Department of Transportation spokesman Travis Phelps told KOMO-TV that investigators are looking into the possibility that an oversize load struck the bridge and triggered the collapse.

The collapse will raise questions about the nation's infrastructure, which has been a popular issue with President Obama, who earlier this year warned against "raggedy" roads and wants to focus more money on rebuilding to improve the economy.

Interstate 5 is closed in both directions, Francis said. Phelps said the collapse means that commuters on the heavily traveled highway will have to find alternate routes "for the foreseeable future.''

"This is going to be a long term situation,'' Phelps said. "This is tragic. Unbelievable.''

The collapse occurred around 7 p.m. PT, Francis said. The location is near Mount Vernon, Wash., in Skagit County, about an hour's drive north of Seattle.

A Skagit Valley Herald reporter at the scene said a sheriff's office rescue boat has arrived and rescue crews were looking for people in the water, the Associated Press reported. The reporter saw one person sitting atop one vehicle in the water and could see a second vehicle as well.

Crowds of people lined the river to watch the scene unfold, the newspaper reported.

KOMO-TV aired video from a helicopter showing the collapsed bridge with rescuers working from shore and a motorboat to search for people.

At least two vehicles, a truck and automobile, could be seen in the water on the collapsed bridge section.

The river did not appear to be deep or fast-flowing at the time of the collapse. KOMO said the depth appeared to be about 10 feet.

KOMO reported that at least two people were taken to a hospital.

The bridge is the main route for traffic between the Seattle metro area and Vancouver, Canada.

The Seattle Times reported that bridge was built in 1955 and was classified by the National Bridge Inventory as "functionally obsolete" in both 2000 and 2010. But it said the Washington Department of Transportation does not list it among its list of "structurally deficient bridges."